Can I charge my iPhone with my MacBook Air?

Yes, absolutely. The USB-C ports on a MacBook Air can charge iPhones, iPads, AirPods, and other USB-C devices. An iPhone draws about 5-10 watts, which has a small impact on your laptop’s battery—maybe 10-15% less runtime over a few hours. It’s fine for a quick top-off, but it’s a convenience trick, not a backup battery.